A Boeing plan to redesign the 787 Dreamliner's fire-plagued lithium-ion batteries has been approved by America's aviation authority, but there was no word on when the planes would be allowed to fly passengers again.
The 787 fleet has been grounded by the Federal Aviation Administration (FAA) and civil aviation authorities in other countries since January 16, following a battery fire on a Dreamliner parked in Boston and a smoking battery that led to the emergency landing of another 787 in Japan.
The 787 is Boeing's newest and most technologically advanced plane. Its grounding marked the first time since 1979 that the FAA had ordered every plane of a particular type to stay out of the air for safety reasons.
The Boeing plan includes changes to the internal battery components to minimise the possibility of short-circuiting, which can lead to overheating and cause a fire. Among the changes are better insulation of the battery's eight cells and the addition of a new containment and venting system, the FAA said in a statement.
Congressman Rick Larsen, who was briefed by the agency, said that if all goes well, the FAA could give final approval by mid- to late April for the 787 to resume flights.
Boeing would still have to retrofit the 50 planes already delivered to eight airlines in seven countries, Mr Larsen said. That could mean the plane would not return to the skies until late April or early May, he said.
First, Boeing's redesigned batteries have to pass 20 separate tests lab, Mr Larsen said, then flight tests would follow.
"If there's any one test that isn't passed, it's back to the drawing board for that particular part of the tests," he said.
So far, test flights of two 787s have been approved - one with a complete prototype of the new battery, the other with only a new, more robust containment box for the battery, Boeing spokesman Marc Birtel said.